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Abstract:

Provided herein is a method of making an integrated circuit device using
copper metallization on 1-3 PZT composite. The method includes providing
an overlay of electroplated immersion of gold (Au) to cover copper metal
traces, the overlay preventing oxidation on 1:3 PZT composite with
material. Also included is the formation of immersion Au nickel
electrodes on the 1-3 PZT composite to achieve pad metallization for
external connections.

Claims:

1. A method of making an integrated circuit (IC) device using copper
metallization on 1-3 PZT composite, comprising: providing an overlay of
electroplated immersion gold (Au) to cover copper metal traces, the
providing preventing oxidation on the 1:3 PZT composite with material;
and forming an immersion of Au nickel electrodes on the 1-3 PZT composite
to provide pad metallization for external connections of the IC.

[0005] Improved concepts are needed for fingerprint touch sensors based on
the use of 1-3 piezo-composite and the principle of ultrasonic
impediography.

BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION

[0006] Embodiments of the present invention are made with respect to
principle sensor performance, sensor design and manufacturing as well as
packaging. Additional hardware and software implementations are described
addressing MTF performance. An improved concept for a fingerprint touch
sensor based on the use of 1-3 piezo-composite and the principle of
ultrasonic impediography is presented. Improvements are made with respect
to principle sensor performance, sensor design and manufacturing as well
as packaging. Additional hard and software implementations are described
addressing MTF performance. The existing ASIC hardware is described
separately in the respective ASIC development description. The software
package for sensor control, data analysis and fingerprint presentations
is implemented and contained in USB software stick already distributed to
customers.

[0007] An exemplary sensor can have an area of up to 1.5'' by 1.6'' and an
element pitch of 500 dpi. More specific features are provided below that
address improving the touch sensor by packaging, sensor design, sensor
construction, software/hardware concepts for MTF control, and various
sensing principles.

[0008] Further features and advantages of the invention, as well as the
structure and operation of various embodiments of the invention, are
described in detail below with reference to the accompanying drawings. It
is noted that the invention is not limited to the specific embodiments
described herein. Such embodiments are presented herein for illustrative
purposes only. Additional embodiments will be apparent to persons skilled
in the relevant art(s) based on the teachings contained herein.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

[0009] The accompanying drawings, which are incorporated herein and form
part of the specification, illustrate the present invention and, together
with the description, further serve to explain the principles of the
invention and to enable a person skilled in the relevant art(s) to make
and use the invention.

[0061] The features and advantages of the present invention will become
more apparent from the detailed description set forth below when taken in
conjunction with the drawings, in which like reference characters
identify corresponding elements throughout. In the drawings, like
reference numbers generally indicate identical, functionally similar,
and/or structurally similar elements. The drawing in which an element
first appears is indicated by the leftmost digit(s) in the corresponding
reference number.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0062] Embodiments of the present invention provide methods and systems
related to integrated circuit (IC) fabrication on 1-3 PZT composite
material. In the detailed description that follows, references to "one
embodiment," "an embodiment," "an example embodiment," etc., indicate
that the embodiment described may include a particular feature,
structure, or characteristic, but every embodiment may not necessarily
include the particular feature, structure, or characteristic. Moreover,
such phrases are not necessarily referring to the same embodiment.
Further, when a particular feature, structure, or characteristic is
described in connection with an embodiment, it is submitted that it is
within the knowledge of one skilled in the art to affect such feature,
structure, or characteristic in connection with other embodiments whether
or not explicitly described.

[0071] 8.--Conductive layer for ESD protection (For the touch sensors we
will need a conductive coating. ideally something we can spin on not much
thicker than what we do with SU8).

[0072] 9.--Vias in composite material (see, for example FIGS. 38-45) vias
are connecting electrodes from one side of the sensor to the other side
facilitating bonding. Feasibility with drilled and subsequently filled
vias have been demonstrated previously; three more via technologies have
been evaluated: vias created in green tiles and vias created within the
dice and fill process as well as vias created by laser drilling.

[0073] 10.--Thermal Compression ACF attach: a device for thermal bonding
developed and approved for mfg.--(FIGS. 46-50).

The major advantages of the US bonding are: [0077] 1) Low temperature
fast bonding time [0078] 2) Less thermal damage to sensor [0079] 3)
Higher throughput

[0080] For bonding the 3050 sensor and bezel as well as the proposed touch
sensor the use of the MicroPack's 130 Dual Head US bonder is of
advantage, whether the US bonding can be successfully done on the 3050
sensor plus bezel prototype assembly. If the test results come out good,
Sonavation can consider MicroPack as not only an US bonding equipment
manufacturer but also one of the Sonavation's sensor assembly houses as
the STARS in Thailand.

[0081] 12--Attach Bezel at same time as Sensor to create absolute flat
surface.

[0115] 41 Clock & Reset synchronization of the surface prior to surface
activation using immersion in palladium (Pd) based solution.

[0116] Current 1-3 composite of falcon geometry pitch 72 um, width 50 um
and pillar height 150 um is approx 50 percent as measured with laser
vibrometry and predicted by FEM modeling. Crosstalk is reduced, if the
interstitional material exhibits a large difference (preferably a lower)
to the PZT, e.g. air. However air will not keep the pillar in place.
Currently Epotek 301-2 is deployed providing sufficient bonding strength
to keep the pillars in place during grinding the process step exerting
the largest force to the pillar during manufacturing. However, material
with much lower acoustic impedance could be employed as for example epoxy
fill with hollow glass spheres having a diameter of <1 um.

[0117] Another possibility are nano porous polymers currently under
development, but with no known source of commercial production.

[0118] Note on Air like Backing of Transducers/Fingerprint touch sensor

[0119] Problem: Air backing is of advantage for ultrasound transducers as
it increases the output amplitude by 30% according to the Redwood
Transient Model. For the fingerprint sensor air backing is vital, as
energy shall be transmitted in the front medium only. In both cases the
sensors front propagation material is soft tissue a suitable backing must
have much lower acoustic impedance approximately 0.1 MRayl as estimated
from earlier calculations.11 Hard backing would be a solution
too. However the hardest material, pure tungsten, has an ac. Impedance of
100 MRay leaving us with reflection coefficient of ˜0.74.

[0120] Particularly for the fingerprint touch sensor the backing is
required for stability.

[0121] Proposed solution: Rough surface. The surface roughness of most
material provides an interface to the fingerprint sensor, which is only
partial in contact with the active sensor. Typically no acoustic contact
is achieved without high static pressure. The reduced contact area of a
rough surface is equivalent to an air like backing and can support the
sensor.

[0122] Backing is provided by a layer sprinkled randomly with bumps having
diameter less than a pillars width. These bumps provide the support for
the sensor. Due to their round shape and small total area the
transmission into the backing is kept low. The average distance between
bumps will be chosen according the bending strength of the 1-3 piezo
composite. For fingerprinting each bump may create a pillar failing
reflecting the front loads. However, if the fingerprint is over sampled,
filtering out those locations will not degrade the final result of the
fingerprint matching schemes. The random scheme is used to destroy phase
coherence for any transmission and wave propagation in the backing

Generating the Bump Feature

[0123] Bumps will be produced by a mold created from a random pattern. The
random pattern is generated by first calculating a sub matrix with side
length of half the stability distance of two supporting points. Bump
locations are then created randomly within each sub-matrix, where the
matrix length is much larger than the bump diameter.

[0124] Non linear contacts at the bottom interface is modified to the
advantage of acoustic impediography for the acoustic load to be estimated
placed on the top and pressed down by a static pressure. For example
spherical random contacts are made at the interface, which under no
static load provide a certain contact area. If the static load is
increased, the contact area increase if a suitable contact point material
is employed, e.g. RTV. If the contact area increases the damping is
increase on locations where the acoustic top load is in acoustic contact
with the sensor. For a sufficient resolution of this improved method a
very flexible 1-3 composite substrate is required.

[0125] Software (contained in the development kit sent to customers: e.g.
MAT

[0126] Libraries

[0127] SonicLib

[0128] Sparrow ASIC control and I/O

[0129] Mapping Tables

[0130] Dynamic Optimization

[0131] Bad Pixel detection and correction

[0132] Multiple ASIC capability

[0133] SonicPal--Platform abstraction layer (per platform)

[0134] Provides abstraction of hardware specific details and certain
operating system functions, such as debug I/O and memory allocation.

[0173] 45 Real-time programmable Rx Tx time-delay templates--they can be
programmed to change as 1 image is captured, or for several image
sequences, which would then be combined during post-processing.

[0174] 46 Real-time programmable "differential" templates--any grouping of
SLUTS, programmable Tx amplitude, and register-settings creates a
template. Several templates are sequenced to produce several temporary
images which are then "differentiated" to extract the high-quality final
image.

[0175] 47 Programmable PLL templates (might include SLUTS and register
settings). May require several PLL templates, slightly varying
off-resonance. Used to analyze the sensor before the finger touches the
sensor. The individual pixel response to varying PLL frequency is used to
predict/calibrate each pixel's sensitivity. (An off-resonance PLL was
used successfully to enhance our original Tiger sensor's MTF.)

[0176] 48 Any combinations of the above that may normalize pixel
excitation across the sensor image to improve MTF.

[0177] 49 Any combinations of the above that may positively affect
standing-wave characteristics of the sensor image to improve MTF.

[0178] 50 Any of the above that can be used to resolve the sensor's static
and temporal noise signature, so that noise reduction can be applied.

[0179] 51 Any combinations of the above, performed both before and after
the finger touches the sensor, to reduce noise, and enhance MTF.

ASIC (defined by ASIC specs already sold to customer see also specs for
Maverick, Sidewinder, Goldfinger, Lotus)

[0180] Digital architecture

[0181] Processor

[0182] Memory (ROM, SRAM, 1T-SRAM, OTP RAM)

[0183] Bus architecture

[0184] DMA controller

[0185] Encryption cores (AES, ECC, SHA, HMAC)

[0186] OTP RAM usage for security keys storage

[0187] Standard host interfaces

[0188] SPI/USB/UART/EBI/SDIO/7816

[0189] High security interface (challenge, encryption, key protocol)

[0190] Random number generator

[0191] External devices interface

[0192] Flash memory

[0193] ROM

[0194] SPI/UART/GPIO

[0195] BOOT timer

[0196] Sensor Controller

[0197] Special sequencing one TX at a time, some RX to minimize peak power
consumption

[0252] 59 Multifrequency Impediography. Use of 2 frequencies, fs and fp
(serial and parallel resonance of the pillar) increases the dynamic range
substantially (e.g. it squares the dynamic range between ridge and
valley). This two frequency method is expanded into even higher
sensitivities if more measurements at several frequencies between fs and
fp as well as above fp and below fs are utilized predicting the load.

[0253] 60 Wavelet impediography. The frequency dependent electrical
impedance around the pillars resonance frequency has typical shape, which
can be described as a wavelet. If a dampening load is applied to the
pillar the wavelet will change its shape. Using mathematical relation of
wavelet analysis will greatly enhance the dynamic range of acoustic
impediography and hence fingerprinting

[0254] 61 Coded excitation will help detecting current change at an
element measured in case the signal level is corrupted by acoustic noise
resulting from crosstalk and wave propagation. The coding is detected by
cross correlation

[0255] There are multiple patterns available for being employed for
correlation which must be evaluated separately. But those will follow the
same regime and are hereby claimed.

[0256] 62 Frequency shift method. A smaller or larger shift to the lower
frequency of fs is observed when pillars are dampened by outer loads.
This shift is detectable and can be used alone or in combination with the
current response for increased SNR and dynamic range of acoustic
impediography.

[0257] 63 Improving mechanical Q

[0258] Mechanical Q is substantially improved and hence dynamic range and
sensitivity of the impediography method if mechanical crosstalk between
elements is reduced. This can be performed in the following ways:

[0275] During operation several transmit lines will be used to speed up
data acquisition. If the location of the lines are chosen in a way that
emitted waves from the transmit lines propagating across the sensor do
not interfere positively on locations currently measured interference
noise is minimized increasing SNR. This condition is realized if the
distance from locations currently measured to the drive lines are not
multiple of the wavelength of the travelling waves i.e. surface waves,
shear and bending waves.

[0276] Current 1-3 composite of falcon geometry pitch 72 um, width 50 um
and pillar height 150 um is approx 50 percent as measured with laser
vibrometry and predicted by FEM modeling. Crosstalk is reduced, if the
interstitional material exhibits a large difference (preferably a lower)
to the pzt, e.g. air. However air will not keep the pillar in place.
Currently Epotek 301-2 is deployed providing sufficient bonding strength
to keep the pillars in place during grinding the process step exerting
the largest force to the pillar during manufacturing. However, material
with much lower acoustic impedance could be employed as for example epoxy
fill with hollow glass spheres having a diameter of <1 um.

[0277] Another possibility are nano porous polymers currently under
development, but with no known source of commercial production.

[0278] Problem. Air backing is of advantage for ultrasound transducers as
it increases the output amplitude by 30% according to the Redwood
Transient Model. For the fingerprint sensor air backing is vital, as
energy shall be transmitted in the front medium only. In both cases the
sensors front propagation material is soft tissue a suitable backing must
have much lower acoustic impedance approximately 0.1 MRayl as estimated
from earlier calculations.22 Hard backing would be a solution
too. However the hardest material, pure tungsten, has an ac. Impedance of
100 MRay leaving us with reflection coefficient of ˜0.74.

[0279] Particularly for the fingerprint touch sensor the backing is
required for stability.

[0280] Proposed solution. the surface roughness of most material provides
an interface to the fingerprint sensor, which is only partial in contact
with the active sensor. Typically no acoustic contact is achieved without
high static pressure. The reduced contact area of a rough surface is
equivalent to an air like backing and can support the sensor.

[0281] Backing is provided by a layer sprinkled randomly with bumps having
diameter less than a pillars width. These bumps provide the support for
the sensor. Due to their round shape and small total area the
transmission into the backing is kept low. The average distance between
bumps will be chosen according the bending strength of the 1-3 piezo
composite. For fingerprinting each bump may create a pillar failing
reflecting the front loads. However, if the fingerprint is over sampled,
filtering out those locations will not degrade the final result of the
fingerprint matching schemes. The random scheme is used to destroy phase
coherence for any transmission and wave propagation in the backing

[0282] A prototype assembly manufacturing plan should be prepared before a
full manufacturing stage. Basically I believe that major equipment
investment can be done after one secure the certain amount of POs from
customers. Meantime, having the prototyping capability to meet marketing
needs is needed with minimum amount of investment.

[0283] Again, it is preferred that the test-bonding the 3050 sensor and
bezel using the

[0284] MicroPack's 130 Dual Head US bonder be used, whether the US bonding
can be successfully done on the 3050 sensor plus bezel prototype
assembly.

[0285] Sensor FEM Model evaluating sensor performance properties for
fingerprinting using impediography: The model is parametric, i.e. all
geometries can be varied accommodating different pitches and in turn
sensor resolution.

CONCLUSION

[0286] It is to be appreciated that the Detailed Description section, and
not the Summary and Abstract sections, is intended to be used to
interpret the claims. The Summary and Abstract sections may set forth one
or more but not all exemplary embodiments of the present invention as
contemplated by the inventor(s), and thus, are not intended to limit the
present invention and the appended claims in any way.